Normal human subjects differ greatly in their reactions to emotional stimuli and situations. Emotional responses can be classified fundamentally as appetitive or aversive, and temperamental variations in motivational systems are believed to be an important mediator of individual differences in response to emotional stimuli. The proposed research applies new methodologies for measuring appetitive and aversive emotion (including startle modification) to the study of normal human temperament and its deviant extremes. Psychopathic personality, which has a constitutional basis and which is marked by striking affective deficits, presents a potent model for the study of emotion and temperament. A series of six studies is proposed to explore psychophysiological markers of temperament in competing appetitive and aversive stimulus contexts, to investigate the temperamental basis of psychopathy and antisocial personality, and to investigate links between emotional deviance in psychopaths and normal variations in temperament. Extending previous work, experiments are proposed to examine affective responding during anticipation of pleasant, neutral, and affectively ambiguous pictorial stimuli, and to examine transfer of affect in the context of more realistic, evocative film presentations. The promise of this research lies in the development of physiologically-based markers of affective individual differences and in an improved understanding of the relationship between psychopathy and normal temperament.